1. Field of the Invention
The invention relates in general to a paper feeding apparatus with a paper size determining means, and more particularly to a paper feeding apparatus detecting paper size by using a to-be-sensed component synchronously moved with a paper guide.
2. Description of the Related Art
Each of a copier, a scanner, a printer and a multi-function peripheral is an electronic product needing a document specification detecting device. So, it is very important to select a suitable document specification detecting device for these electronic products.
FIG. 1 (Prior Art) is a schematic illustration showing a rear surface of a paper tray of a conventional copier. Referring to FIG. 1, the conventional paper tray 100 includes a blade-like plate 110. The blade-like plate 110 contains a fulcrum 120, a section track 130, protrusions 140 and a paper guide 150 movable on the section track 130. When the paper guide 150 slides along the section track 130 and abuts against an edge of the paper, the blade-like plate 110 is rotated about the fulcrum 120. The protrusions 140 having different sizes respectively correspond to different paper sizes. When the paper guide 150 abuts against the edge of the paper, the protrusion 140 corresponding to the size of the paper being used shields a sensing path of a photosensor 115. The size of the paper may be judged according to the size of the range of the sensing path being shielded.
At present, the blade-like plate 110 is manufactured by way of injection molding or sheet metal pressing. These methods have the following drawbacks.
First, the blade-like plate formed by way of injection molding has the drawbacks of the poor rigidity, the contraction and the buckle.
Second, the blade-like plate formed by way of sheet metal pressing has the problems of the burr and the heavy weight.
In addition, the conventional paper feeding apparatus capable of detecting the paper size has the section track 130 having a lot of positions and angles corresponding to the paper with different paper sizes. So, when the paper size is rapidly switched, the paper guide cannot slide smoothly in the section track 130. In addition, the exterior of the blade-like plate 110 is like a long blade, and the swinging area of the blade-like plate 110 is large. Thus, the rear portion of the paper feeding apparatus needs a larger area coverage, thereby causing the bulkiness in the overall assembly.